A universal joint transmission is usually formed by at least two telescopic transmission shafts, at the ends of which articulated joints are mounted which are capable of transmitting the motion and the torque to elements that rotate about oblique axes and on different planes. Such transmissions are widespread in the agricultural field, for example in order to connect equipment to the power take-off of the tractor. In order to meet the conformity and safety requirements, universal joint transmissions must be provided with suitable protections that isolate the rotating elements from the external environment and at the same time do not limit the articulation and the moving mechanisms of the system.
In general, the protection is an integral part of a universal joint transmission and is formed by two flexible protections arranged at the end of two telescopic and concentric tubular protections capable of following the relative movements among the elements of a universal joint transmission.
Currently, there are several types of protection on the market, which, however, are not devoid of drawbacks. Among the drawbacks one must certainly include the fact that they make the assembly and disassembly of the universal joint on/from the power take-off very laborious. Furthermore, the protections of the known type make it difficult to maintain the universal joint transmission, for example by preventing direct access to the parts to be lubricated of the universal joint transmission.
In protections of the known type, the flexible hoods that protect the joints are fixed, for example, by means of pairs of flanges, to the tubular elements that protect the transmission shafts, and are supported by supporting rings, each of which slides in a slot provided in the fork of the joint. However, said components are coupled to each other, for example by means of screws, and access to the joint, for assembling and disassembling the universal joint transmission, is therefore very laborious for the operator.
In other protective solutions of the known type, the flexible hoods that protect the joints can be fixed to the tubular elements, that protect the transmission shafts, by means of supporting rings or pairs of flanges fixed on the tubular protective elements by way of snap action engagement means. In these cases, however, the operator, in order to be able to disengage the hood and access the joint, must act simultaneously on all the snap action engagement points by means of tools, and this occupies simultaneously both hands and is particularly awkward. Furthermore, since reengagement occurs by repositioning the hood and reengaging the snap action means until interlocking has occurred, a partial reengagement of the snap action means can lead the operator to think that the hood is fixed correctly, when this condition actually is not occurring.